Interface Architecture for Fine Grained Polycrystalline Materials by Grain Boundary Control and Design

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This project was conducted for development of interface architecture towards innovation in performance of fine grained porycrystalline materials through the grain boundary. control and design. Main results obtained are as follows.1. Development of FE-SEMIEBSP Analysis of Grain Boundary Character in Fine Grained Polycrystalline Materials : We confirmed that a newly developed FE-SEM/EBSP/OIM system made it possible to analyze the grain boundary character in polycrystalline materials having nano-scale grains.2. Control of lntergranular Brittleness : Intergranular brittleness of such polycrystalline materials as molybdenum which is considered as intrinsically brittle material can be improved by control of the grain boundary character distribution (GBCD) and the grain boundary connectivity.3. Application of Magnetic Field for Evolution of Microstructures in Ferromagnetic Materials : Magnetic field was applied to sintering of pure iron compacts for development of controlling techniques of mi … More crocircuitries. As the results, both densification and grain growth are found to be enhanced by the magnetic sintering. Also, bicrystal experiments using a Fe-Si alloy revealed that the grain boundary migration rate was increased by the magnetic field, and that the magnetic anisotropy of the material can provide a driving force for grain boundary migration. in addition, the magnetically sintered iron showed a high performance of magnetic properties comparing with a non-magnetically sintered one.4. Occurrence of a giant strain by magnetic field induced martensite transformation : It was found that a rapidly solidified and annealed ferromagnetic Fe-Pd alloy shows a giant strain ten times as larger as standard magnetostrictive materials ; the giant strain is probably caused by the magnetic field induced martensite transformation. Also, the shape memory effect was demonstrated by removal of the magnetic field. Furthermore, the textured grain structure was found to provide a high response in occurrence of the giant strain to weak magnetic field. Less